add README

README.md

@@ -1 +1,19 @@
 # Kernel for Raspberry Pi 32 bits, for usage in gokrazy
+
+Usage
+
+```
+GOARCH=arm ./gokr-packer \
+		-kernel_package=github.com/oliverpool/kernel-rpi-os-32/dist \
+		-firmware_package=github.com/oliverpool/firmware-rpi/dist \
+		-serial_console=disabled \
+		github.com/gokrazy/hello
+```
+
+## Manual compilation
+
+```
+go run cmd/compile/main.go
+```
+
+It will compile the kernel located in `linux-sources` and copy the resulting files in the `dist` folder.